This invention relates in general to emergency locking safety belt retractors and more specifically to such retractors employing means for reducing the belt tension in the safety belt during use by the operator to produce what is commonly called a "low tension zone", a zone of belt movement during use by the occupant when the rewind bias on the belt storage reel is relieved or reduced.
In prior art safety belt retractors, as in U.S. Pat. No. 3,834,646 (Heath) the belt tension is completely relieved by means activated by belt manipulation to hold the belt storage reel against retraction. However, it has been found that in some instances it is desirable to have a low tension rewind bias applied to the belt during the so-called "low tension zone" use of the belt so that it will have a rewind bias which can be utilized for deactivating the low tension producing means and provide for a full tension rewinding effect upon merely allowing the belt to retract or rewind naturally. One such improvement is disclosed in my copending application, U.S. Ser. No. 680,111 filed Apr. 26, 1976 now U.S. Pat. No. 4,026,494 in which I disclose a means for providing a low-tension zone effect through the provision of a counterbiasing spring. In that application disclosure, the normally provided retractor rewind spring is selectively counteracted upon by a counterbiasing spring to produce the low-tension zone mode. I have recognized that it would be desirable to produce such a low-tension zone mode of operation for a retractor employing spring means which act together, or independently of one another, as opposed to the counterbiasing effect of my prior invention.